The type of barrier system disclosed in U.S. Pat. No. 4,806,044 is adapted to be lifted by a mobile transfer and transport vehicle and moved to a selected position on a roadway or the like. Moveable barrier systems of this type find particular application at roadway construction sites and on roadways and bridges whereat the groupings of incoming and outgoing lanes of traffic must be varied, particularly during commute hours.
The barrier system comprises a series of interconnected concrete modules hinged together to form a continuous chain. The cross-section of each module is similar to that of a "Jersey-type" barrier, but has a T-shaped top section. A standard module has a height approximating thirty-two ins., a length approximating thirty-seven ins. and weighs approximately 1400 lbs. The modules are pivotally connected together by inserting a steel pin through hinge components attached to the ends of each adjacent pair of modules.
The self-propelled transfer and transport vehicle includes a conveyor system for shifting the barrier system laterally across the roadway from a first side to a second side of the vehicle. The shift or lateral displacement of the barrier system can be normally varied from four to eighteen feet. The conveyor system includes a plurality of guide and support wheels or rollers that function to engage beneath the T-shaped top section of the modules for lifting and transfer purposes.
The modules move through a serpentine-like transfer path (elongated "S" curve) for accurate positioning thereof to define a repositioned lane line. The modules are moved at a speed approximating five mph through the conveyor. Oftentimes, the vehicle must negotiate curved sections of roadways whereby the barrier system is likewise curved.
U.S. Pat. Nos. 4,806,044 and 4,828,425, both assigned to the assignee of this application, each address the long-standing problem of providing a barrier system that will elongate or contract to accommodate positioning of the system at varied radii on a curved roadway. The original barrier system, disclosed in U.S. Pat. No. 4,500,255, is particularly useful for straight-line roadway applications and utilizes a hinge connection between each adjacent pair of modules. The hinge connection includes aligned circular holes, formed in overlying hinge plates, adapted to receive a hinge pin therethrough. Even when the holes are lined with a thin (e.g., 1/8" wall thickness) elastomeric bushing, the modules may not elongate as a unit when the system is moved radially on a curved roadway.
For example, it has been determined that when the barrier system is moved from a 1,200 ft. radius to a 1,212 ft. radius, the composite length of the barrier system must increase by approximately 0.25 in. for each three feet in length of the barrier system to effectively accommodate this new position on the same, curved roadway. Conversely, repositioning of the barrier system radially inwardly to a new position on the curved roadway, having a radius of curvature of 1188 ft., will require a corresponding contraction of the composite length of the lane barrier system. In the above example, it should be understood that the ends of the barrier system are located at the same relative radial position on the curved roadway to thus require the aforementioned composite elongation or retraction of the system.
One solution to the latter problem of compensating for curvatures of varied radii on a curved roadway has been to substitute elongated slots for the pin-receiving circular holes, formed in the hinge plates. The slots allow the lane barrier system to assume various radii, as described in the above example. However, it has proven further desirable to return the spacing between each adjacent pair of modules to a nominal one when the barrier system is loaded onto a transfer vehicle and thereafter returned to its normal position on a roadway, e.g., the above-mentioned radius of 1200 ft.
Repeated transfer of the modules, having slotted hinge plates, will tend to "stack-up" the modules towards one of the ends of the lane barrier system which may interfere with effective transfer and placement of the modules in their correct positions. In particular, it is desirable to maintain the pivot pin between each adjacent pair of modules at a centered position therebetween (and reestablish the nominal spacing) when the barrier system is returned to its nominal position on a roadway. This feature, when achieved, facilitates the efficient transfer of the system by the type of transfer and transport vehicle described in the above-referenced patents.
The invention covered by above-referenced U.S. Pat. No. 4,806,044 solves this problem by providing elastomeric pads in the hinge connections, between each pair of adjacent modules of the barrier system, whereby the modules will: (1) elongate or contract to assume a composite varied length different from their nominal composite length in response to the imposition of a load on the system, and (2) return the modules to their nominal composite length when the load is removed. The invention covered by U.S. Pat. No. 4,828,425 solves the problem by preloading the hinges, connecting adjacent pairs of modules together, to facilitate a high degree of uniform spacing between the modules when they are moved through the conveyor of a self-propelled transfer and transport vehicle for subsequent replacement on a roadway.